It's not behind a paywall, so I think I can reproduce it in its entirety
here (go read New Scientist anyway). In general I'm pretty pleased with it,
although there's one point I'd like to explore: "In
reality, climate change is unlikely to have a single catastrophic point of
failure, and might, to stretch the analogy, be a series of increasingly severe
drops."

Here's the problem with the analogy, and with 'targets' in general. The
waterfall is a binary outcome, increases in temperature are not. 1.6 degrees is
not the same as 3.6. A better analogy here would be a series of rapids (I like
white water canoeing by the way. Go Team 'Stupid Geese'). One might imagine
that the start of the rapids are gentler and, that for the first few seconds we
might be able to paddle upstream and get to the bank. This is actually a better
analogy for greenhouse gas removal, it may return us to safety even after we've
overshot. Every metre we travel into the rapids the further we've got to paddle
back and, importantly, the more severe the outcome. Is this a problem inherent
with targets? Maybe so. Does missing 1.5 mean anything politically. Will it
generate political apathy? or galvanise the political classes. Who knows? I
suspect an aspirational target is, overall, a net positive but without
addressing how we might stay below 1.5 it is fairly meaningless.
I've applied to be a lead author on the IPCC 1.5 degree report. I'd be very
surprised if anyone associated with SRM gets selected, so politically toxic is
the idea. That, unfortunately, is going to have to change...

_________

The Paris climate agreement’s goal of stopping the world warming more than 1.5 °C produced a strong but mixed response from scientists. While most welcomed its intention, and the marker it put down, some, including me, were also alarmed,wondering how that goal might be achieved. Here’s the truth, made all the more plain by thepossible withdrawal of the US from the Paris agreement: if we wish to stay below 1.5 °C we have to deliberately intervene in the global climate system on a massive scale. Nothing of that scope has ever been attempted. The worst implications of a warmer world –sea-level rise, crop failure and population displacement – would make it immoral not to act if we can. These potential impacts look much less far-fetched than they did even a decade ago. We are nearing the point at which we must act. Hence the growing call for a full and frank discussion of allgeoengineering methods. These would aim to alter the planet’s radiation budget, for example, by pumping reflective or cloud-altering particles into the air. In particular,field trials of radiation management (RM) methods to cool the Earth now need immediate support.

Why the urgency? Because we are in a raft without paddles heading towards a waterfall and we’re running out of options. We could paddle for the bank with our hands. That’s like curbing carbon emissions and requires co-operation and leadership. But we’ve left it too late – we’re too near the waterfall to make it to safety this way. We could build makeshift paddles to row quicker. This is like greenhouse gas removal, the development of technologies that suck carbon dioxide out of the air – so-callednegative emissions. But it looks doubtful we can make the paddles in time. Or we could brace ourselves for the inevitable, strap ourselves in and those that have them might put on hard hats in the hope they are sufficient. This is adaptation, like bolstering coastal defences or relocating threatened populations and letting the waters rise.Alternatively, we could swim for it. But that’s risky as the water looks cold and not everyone can swim. This is like using radiation management. You can do this quickly and relatively cheaply but the outcome is less certain. This option, given its potential for rapid deployment,has been woefully under-researched.

The waterfall analogy highlights the importance of information. If we knew how long we have before we fall over the waterfall, the severity of the fall, the amount of time it would take to make a paddle and the temperature and depth of the water you could make a more informed decision. More geoengineering research will give us more information. Fortunately, these options are not mutually exclusive. In reality, climate change is unlikely to have a single catastrophic point of failure, and might, to stretch the analogy, be a series of increasingly severe drops. Of course it makes sense to properly explore all options – continue to wean ourselves off carbon, develop negative emissions technologies and brace for the impacts of climate change. But we must also “test the water” in case we decide to swim for it. That means considering properly, through research and a more open and honest discussion, the unpalatable choice of climate engineering through radiation management.

Over and over, as I have no PhD after my name, I am ignored by prestigious people espousing climate engineering. We keep hearing about the awesome ability of scientists to admit that their hypothesis was wrong. But I'm not seeing that.

What I am seeing is the same shallow ego-trips of teenagers trying out their adult wings-- cattiness, bullying, name calling, ignoring unpleasant realities, and not seeing beyond their own noses.

Here's a better way to get back below 350 ppm CO2. See what you thinK:

HOW TO REVERSE CLIMATE CHANGE !

Mycorrhizal fungi pulls more CO2 from the atmosphere than any other method. In 15-20 years it could get us back to 350 ppm from the human-caused 400+ it is now.

Regenerative Agriculture practitioners found humanity’s 10,000-year-old mistake: plowing. Turning the soil kills the mycorrhizal fungi that, in nature, coat every root hair and bring minerals to the plant in exchange for 20 to 50% of the sugars photosynthesized by the plant.

David Johnson, PhD, of the U. of New Mexico, finds that inoculating cover crops on only half of the world’s fallow land would sequester enough CO2 in the soil. Meanwhile, corporate and government aerosol spraying ('chemtrails'), supposedly done to cool the climate, actually warms earth.

Tests show that using fungi costs less and works faster, on a big enough scale, than any other method. Plus, using fungi doubles yields with no extra water, makes ‘traditional’ seeds outperform GMO seeds, and ends the need for nitrate fertilizer.